Histoanatomy of anal glands

Incidence of anal fistula after pyogenic perianal abscess drainage in Kingdom of Bahrain

PURPOSE

Perianal fistula is one of the most common anorectal diseases in adult patients, especially men. A relationship between pyogenic perianal abscess and fistula formation is established in multiple domains. This is the first exploration of such association among patients in the country as no related study has been published in Bahrain. We expect this study to be a foundation for future protocols and evidence-based practice.

METHODS

A retrospective study was conducted in Salmaniya Medical Complex of Bahrain. A total of 109 patients with a diagnosis of anal abscess were included between 2015 and 2018. Data were collected from the electronic files database used in Salmaniya Medical Complex (iSeha) as well as phone calls to the patients. Collected data were analyzed using statistical software.

RESULTS

The most predominant presentation of perianal abscess was pain. Over 50% of abscesses were classified as perianal (56.9%) and among those, left-sided abscesses were more common, followed by right-, posterior-, and anterior-sited, respectively. No recurrence of abscess was recorded among 80% of patients. A fistula developed following abscess drainage in 33.9% of patients. Most fistulas (37.8%) were diagnosed within 6 months or less from abscess drainage. Posterior fistulas were the most common, followed by anterior and left-sided fistulas.

CONCLUSION

The incidence of anal fistula in Bahrain after perianal abscess was 33.9%. Most of the patients who developed a fistula following pyogenic abscess drainage were males and above the age of 40 years. The most common site for fistula was posterior.

Crohn's Disease-Associated and Cryptoglandular Fistulas: Differences and Similarities

Perianal fistulas are defined as pathological connections between the anorectal canal and the perianal skin. Most perianal fistulas are cryptoglandular fistulas, which are thought to originate from infected anal glands. The remainder of the fistulas mainly arises as complications of Crohn's disease (CD), trauma, or as a result of malignancies. Fistulas in CD are considered as a consequence of a chronic and transmural inflammatory process in the distal bowel and can, in some cases, even precede the diagnosis of CD. Although both cryptoglandular and CD-associated fistulas might look similar macroscopically, they differ considerably in their complexity, treatment options, and healing rate. Therefore, it is of crucial importance to differentiate between these two types of fistulas. In this review, the differences between CD-associated and cryptoglandular perianal fistulas in epidemiology, pathogenesis, and clinical management are discussed. Finally, a flow chart is provided for physicians to guide them when dealing with patients displaying their first episode of perianal fistulas.

The Intersection of Human and Veterinary Medicine-A Possible Direction towards the Improvement of Cell Therapy Protocols in the Treatment of Perianal Fistulas

The effective treatment of perianal fistulizing Crohn's disease is still a challenge. Local administration of mesenchymal stromal cells (MSCs) is becoming a part of accepted treatment options. However, as a fledgling technique, it still can be optimized. A new trend in translational research, which is in line with "One Health" approach, bases on exploiting parallels between naturally occurring diseases affecting humans and companion animals. Canine anal furunculosis (AF) has been indicated as condition analogous to human perianal Crohn's disease (pCD). This narrative review provides the first comprehensive comparative analysis of these two diseases based on the published data. The paper also outlines the molecular mechanisms of action of MSCs which are likely to have a role in modulating the perianal fistula niche in humans, and refers them to the current knowledge on the immunomodulatory properties of canine MSCs. Generally, the pathogenesis of both diseases shares main determinants such as the presence of genetic predispositions, dysregulation of immune response and the relation to intestine microbiota. However, we also identified many aspects which should be further specified, such as determining the frequency of true fistulas formation in AF patients, elucidating the role of TNF and Th17 pathway in the pathogenesis of AF, or clarifying the role of epithelial-to-mesenchymal transition phenomenon in the formation of canine fistulae. Nevertheless, the available data support the hypothesis that the results from testing cell therapies in dogs with anal furunculosis have a significant translational value in optimizing MSC transplants procedures in pCD patients.

Benign Anorectal Disorder Management in Low-Resource Settings

There are many benign anorectal disorders, which can make patients seek care. In low-resource settings, the incidence of those pathologies is not different from the industrialized and western world. However, an interesting difference colorectal surgeons and gastroenterologists can face is the fact that many patients do not seek help or are not aware and have little opportunities to be helped. Latin America population is estimated to be around 8% of the world population, with Brazil having the largest percentage. Infectious diseases, which were previously under control or were steadily declining, have emerged. For example, we have seen resurgence of dengue, malaria, and syphilis in pregnancy, as well as other sexually transmitted diseases that can affect the anorectal region. In this article, we will address the most common benign anorectal disorders.

Intersphincteric Exploration With Ligation of Intersphincteric Fistula Tract or Attempted Closure of Internal Opening for Acute Anorectal Abscesses

BACKGROUND

Acute anorectal abscesses of cryptoglandular origin are commonly managed by incision and drainage, which results in fistula development in up to 73% of cases, requiring subsequent definitive fistula surgery. However, given that fistula tracts may already be present at the initial presentation, primary closure of the tract as secondary prevention of fistula formation, using ligation of intersphincteric fistula tract, may be useful.

OBJECTIVE

This study aims to examine the feasibility and outcomes of performing intersphincteric exploration with ligation of intersphincteric fistula tract or attempted closure of internal opening for acute anorectal abscesses.

DESIGN

This is a retrospective study of patients with acute anorectal cryptoglandular abscesses who underwent surgery between January 2014 and December 2016.

SETTINGS

The patients were treated at a tertiary referral center in Thailand.

PATIENTS

Eighty-six patients with acute anorectal abscesses without previous surgery were included.

INTERVENTIONS

Intersphincteric dissection was performed. Further surgical intervention was dependent on the intersphincteric findings.

MAIN OUTCOME MEASURE

The main outcome measure was the 90-day healed rate.

RESULTS

Of the 86 patients, 3 had low intersphincteric abscesses, 26 had low transsphincteric abscesses, 25 had anterior high transsphincteric abscesses, 27 had posterior high transsphincteric abscesses, and 5 had high intersphincteric abscesses. Ligation of intersphincteric fistula tract was successfully performed in 66 patients with an identifiable intersphincteric tract. Intersphincteric exploration with attempted closure of the internal opening was performed in the remaining 20 patients. The success rates were 86% and 70%. Unidentified internal opening and intersphincteric pathology were risk factors for nonhealing. No patients reported fecal incontinence postoperatively.

LIMITATIONS

The limitation of this study is its retrospective nature and that all operations were performed by a single surgeon; therefore, the results may vary according to the individual surgeon's expertise.

CONCLUSIONS

Fistula tract formation was found in most cases of acute anorectal abscesses. Definitive surgery using this strategy provides promising results. See Video Abstract at http://links.lww.com/DCR/B451.

EXPLORACIN INTERESFINTRICA CON LIGADURA DEL TRAYECTO EN LA FSTULA INTERESFINTRICA O INTENTO DE CIERRE DEL ORIFICIO INTERNO EN ABSCESOS ANORRECTALES AGUDOS

ANTECEDENTES:Los abscesos anorrectales agudos de origen criptoglandular, comúnmente se manejan mediante incisión y drenaje, lo que resulta en el desarrollo de una fístula hasta en un 73% de los casos, requiriendo posteriormente cirugía definitiva de la fístula. Sin embargo, dado que los trayectos de la fístula ya pueden estar inicialmente presentes, puede ser útil el cierre primario del trayecto, como prevención secundaria en la formación de la fístula, mediante la ligadura del trayecto de la fístula interesfintérica.OBJETIVO:El estudio tiene como objetivo, examinar la viabilidad y los resultados en realizar exploración interesfintérica, con ligadura del trayecto de fístula interesfintérica o intento de cierre del orificio interno para abscesos anorrectales agudos.DISEÑO:Se trata de un estudio retrospectivo de pacientes con abscesos criptoglandulares anorrectales agudos, que fueron operados entre enero de 2014 y diciembre de 2016.AJUSTES:Los pacientes fueron tratados en un centro de referencia terciario en Tailandia.PACIENTES:Se incluyeron 86 pacientes con abscesos anorrectales agudos, sin cirugía previa.INTERVENCIONES:Se realizó disección interesfintérica. La intervención quirúrgica adicional dependió de los hallazgos interesfintéricos.PRINCIPALES MEDIDAS DE RESULTADO:La principal medida de resultado, fue la tasa de cicatrización a 90 días.RESULTADOS:De los 86 pacientes, hubo 3 abscesos interesfintéricos bajos, 26 abscesos transesfintéricos bajos, 25 abscesos transesfintéricos anteriores altos, 27 abscesos transesfintéricos posteriores altos y 5 abscesos interesfintéricos altos. La ligadura del tracto de la fístula interesfintérica, con tracto interesfintérico identificable, se realizó con éxito en 66 pacientes. Se realizó exploración interesfintérica, con intento de cierre del orificio interno en los 20 pacientes restantes. Las tasas de éxito fueron 86% y 70% respectivamente. Orificio interno no identificado y patología interesfintérica, fueron factores de riesgo para la falta de cicatrización. Ningún paciente reportó incontinencia fecal posoperatoria.LIMITACIONES:La limitación de este estudio, es su naturaleza retrospectiva y que todas las operaciones fueron realizadas por un solo cirujano, por lo tanto, los resultados pueden variar según la experiencia de cada cirujano.CONCLUSIONES:En la mayoría de los casos de abscesos anorrectales agudos, se encontró formación de trayectos fistulosos. La cirugía definitiva con esta estrategia, proporciona resultados prometedores. Consulte Video Resumen en http://links.lww.com/DCR/B451.

Incidence of fistula after management of perianal abscess

Background Perianal fistula is among the most common anorectal diseases encountered in adults, men are more prone to be affected than women. There is a close relationship of abscess and fistula in etiology, anatomy, pathophysiology, therapy, complications and morbidity, it is appropriate to consider them as one entity.

Aim of study To determine the incidence of fistula formation and recurrent abscess in a sample of Iraqi patients in Baghdad and decide whether primary fistulotomy should be performed at the time of incision and drainage of perianal abscesses.

Patients and methods A retrospective study of 68 patients with perianal abscess operations conducted in Baghdad. They underwent incision and drainage under either local or general anesthesia at Al-Kindy Teaching Hospitals and private hospitals over a 15-year period from January 2000 to December 2015. Their ages ranged from 20 to 68 years (40.21 ± 1.34) males (63/68) (92.64%) were more than females (5/68) (7.35%). Patients were treated with incision over the abscess under anesthesia and drainage of the abscess was done. The patients were followed up for an average 18 months (range 12–24 months) after abscess drainage or until a fistula appeared and abscess recurrence.

Results The study group comprised of 68 (92.64%) patients with perianal abscess with a median age 39 years (range 20–68 years). The mean follow-up period was identified to be 18 months (range 12–24 months). Males (63/68) (92.64%) were more than females (5/68) (7.35%). The incidence of fistula formation after follow up, the patients with perianal abscess after incision and drainage was 31/68 (45.58%) and males (30/31) (44.11%) were more than females (1/31) (1.47%). The most common site was posterior then left lateral position. The percentage of patients with recurrent abscess n = 6 (8.82%)were lower than fistula formation n = 31 (45.58%). The percentage of males n = 4/6 (5.88%) were more than females 2/6 (2.94%).

Conclusions The incidence of anal fistula in a sample of Iraqi patients with perianal abscess was 45.58% and percentage of recurrence of perianal abscess was 8.82%. To avoid division of anal sphincter muscle, secondary fistulotomy is advised to be done later when anal fistula will be formed.

Three-cavity clearance for perianal abscess: Theoretical basis and progress in clinical application

Three-cavity clearance (TCC) is an innovative technique that completely preserves anal sphincter, which can effectively reduce the probability of postoperative anal fistula formation and the recurrence of abscess, has small trauma and a low risk, and deserves further promotion and study clinically. In this paper, we discuss the theoretical basis, clinical application, and related problems of TCC for perianal abscess.

A Comparative Immunohistochemical Study of Anal Canal Epithelium in Humans and Swine, Focusing on the Anal Transitional Zone Epithelium and the Anal Glands

To better understand the cellular origins and differentiation of anal canal epithelial neoplasms, the immunohistochemical profiles of the anal canal epithelium in humans and swine were evaluated. Formalin-fixed tissue sections were immunostained for mucin (MUC: MUC2, MUC5AC, MUC5B), desmoglein 3 (DGS3), p63, CDX2, SOX2, and α-smooth muscle actin (α-SMA). The anal transitional zone (ATZ) epithelium covered the anal sinus and consisted of a stratified epithelium with mucous cells interspersed within the surface lining. Anal glands opened into the anal sinus. Ducts and acini of intraepithelial or periepithelial mucous type were the main structures of human anal glands, whereas those of swine were compound tubuloacinar mixed glands. Distal to the ATZ epithelium, non-keratinized stratified squamous epithelium merged with the keratinized stratified squamous epithelium of the perianal skin. MUC5AC expression predominated over MUC5B expression in the ATZ epithelium, while MUC5B expression was higher in the anal glands. SOX2 was positive in the ATZ epithelium, anal glands, and squamous epithelium except in the perianal skin. In humans, DGS3 was expressed in the ATZ epithelium, anal gland ducts, and squamous epithelium. p63 was detected in the ATZ epithelium, anal glands, and squamous epithelium. Myoepithelial cells positive for α-SMA and p63 were present in the anal glands of swine. Colorectal columnar cells were MUC5B⁺ /MUC2⁺ /CDX2⁺ /MUC5AC^- /SOX2^- . The ATZ epithelium seems to be a distinctive epithelium, with morphological and functional features allowing smooth defecation. The MUC5AC⁺ /SOX2⁺ /MUC2^- /CDX2^- profile of the ATZ epithelium and anal glands is a useful feature for diagnosing adenocarcinoma arising from these regions. Anat Rec, 301:796-805, 2018. © 2017 Wiley Periodicals, Inc.

Pathogenesis and persistence of cryptoglandular anal fistula: a systematic review

Anal fistulas continue to be a problem for patients and surgeons alike despite scientific advances. While patient and anatomical characteristics are important to surgeons who are evaluating patients with anal fistulas, their development and persistence likely involves a multifaceted interaction of histological, microbiological, and molecular factors. Histological studies have shown that anal fistulas are variably epithelialized and are surrounded by dense collagen tissue with pockets of inflammatory cells. Yet, it remains unknown if or how histological differences impact fistula healing. The presence of a perianal abscess that contains gut flora commonly leads to the development of anal fistula. This implies a microbiological component, but bacteria are infrequently found in chronic fistulas. Recent work has shown an increased expression of proinflammatory cytokines and epithelial to mesenchymal cell transition in both cryptoglandular and Crohn's perianal fistulas. This suggests that molecular mechanisms may also play a role in both fistula development and persistence. The aim of this study was to examine the histological, microbiological, molecular, and host factors that contribute to the development and persistence of anal fistulas.

Infectious Diseases Perspective of Anorectal Abscess and Fistula-in-ano Disease

BACKGROUND

Anorectal abscess and fistula-in-ano is a rare disease with an exemplary prognosis. Most patients are diagnosed with cryptoglandular disease but unusual infections raise difficult antimicrobial management challenges.

METHODS

All primary references identified in PubMed, EMBASE, the ISI Web of Knowledge database and the Cochrane Library, published between 1960 and 2015, using the keywords "anorectal abscess," "fistula-in-ano," "perianal abscess," or "perianal fistula" or all, were uploaded into a database. The databases were also interrogated using keywords specific for each infection type studied.

RESULTS

In all, 52 relevant primary medical publications were identified. There were also 4 relevant organizational standards guideline publications, 1 relevant review and 4 historical publications about the diagnosis and outcomes of anorectal abscess and fistula-in-ano with data derived primarily from prospective and retrospective trials as well as institutional case series to provide an evidence level opinion. The use of antimicrobial therapy in combination with surgical incision and drainage in the treatment of cryptoglandular disease has failed to improved healing times or reduce recurrences or both. Based on limited data, routine antimicrobial therapy may benefit patients with significant comorbid conditions, extensive cellulitis and systemic symptoms. For patients with unusual infecting pathogens (eg, Mycobacterium tuberculosis, Actinomyces species and Chlamydia species) outcomes are favorable with selected antimicrobial therapy agents of various durations.

CONCLUSION

Surgical incision and drainage is the main treatment for anorectal abscess and fistula-in-ano, but a select group of patients with unusual infections benefit from tailored prolonged antimicrobial therapy with the overall recurrence rate remaining low.

Is modern management of fistula-in-ano acceptable?

Fistula-in-ano has been managed by a number of techniques and there remains no consensus on the most appropriate management for all patients. The mainstay of any treatment balances the need to control sepsis vs the risk of potential incontinence post-intervention. Management should focus on the primary source of sepsis.

Defecation 2: Internal anorectal resistance is a critical factor in defecatory disorders

BACKGROUND

The aim of this study was to test our hypothesis that the reason why imaging is of little assistance in diagnosing "constipation" causes may be related to the high sensitivity of internal anorectal flow resistance in defecation to small changes in geometry. We applied a mathematical model to describe the effects on flow mechanics of observed changes in the shape of the rectum and anus during defecation.

METHODS

Three groups of patients were studied with video proctograms. Group 1 comprised 4 patients with normal defecation studied with video proctography or magnetic resonance imaging (MRI). Group 2 comprised 8 patients with fecal incontinence, studied by video X-ray electromyography. Group 3 comprised 8 patients with constipation evaluated by video MRI.

RESULTS

Three muscle vectors open the anorectal angle prior to defecation, causing the anorectal luminal diameter to increase to approximately twice its resting size. These vectors are forwards (anterior wall), backwards and downwards (posterior wall). Resistance to passage of a fecal bolus through the anorectum is determined by viscous friction against the anorectal wall and by the energy required to deform the bolus as it flows. The observed changes in anorectal geometry serve to reduce both the viscous friction in the anus and the deformation of the bolus, which reduces the force required to facilitate its passage through the anus. For example, if the effective diameter of the anus is doubled during defecation, the frictional resistance is reduced by a factor of 8.

CONCLUSIONS

The sensitivity of flow resistance to geometry explains why MRI or computed tomography (CT) scans taken during defecation are not often helpful in diagnosing causation. Small changes in geometry can have a disproportionate affect on flow resistance. Combining accurate directional measurements during dynamic MRI or CT scans taken during defecation with observations of bolus deformation, and if possible, simultaneous anorectal manometry, may provide clinically helpful insights on patients with anorectal evacuation disorders.

German S3 guideline: anal abscess

BACKGROUND

The incidence of anal abscess is relatively high, and the condition is most common in young men.

METHODS

A systematic review of the literature was undertaken.

RESULTS

This abscess usually originates in the proctodeal glands of the intersphincteric space. A distinction is made between subanodermal, intersphincteric, ischioanal, and supralevator abscesses. The patient history and clinical examination are diagnostically sufficient to establish the indication for surgery. Further examinations (endosonography, MRI) should be considered in recurrent abscesses or supralevator abscesses. The timing of the surgical intervention is primarily determined by the patient's symptoms, and acute abscess is generally an indication for emergency treatment. Anal abscesses are treated surgically. The type of access (transrectal or perianal) depends on the abscess location. The goal of surgery is thorough drainage of the focus of infection while preserving the sphincter muscles. The wound should be rinsed regularly (using tap water). The use of local antiseptics is associated with a risk of cytotoxicity. Antibiotic treatment is only necessary in exceptional cases. Intraoperative fistula exploration should be conducted with extreme care if at all; no requirement to detect fistula should be imposed. The risk of abscess recurrence or secondary fistula formation is low overall, but they can result from insufficient drainage. Primary fistulotomy should only be performed in case of superficial fistulas and by experienced surgeons. In case of unclear findings or high fistulas, repair should take place in a second procedure.

CONCLUSION

In this clinical S3 guideline, instructions for diagnosis and treatment of anal abscess are described for the first time in Germany.

Immunophenotypic Characterization of Anal Gland Carcinoma: Loss of p63 and Cytokeratin 5/6

Anal gland carcinoma (AGC) is a rare perianal invasive cancer composed of tubular glands lined by cuboidal epithelium. The clinical features and histogenesis of AGC are not well understood and its origin from anal glands is often difficult to prove. Little is known about immunophenotypic features of AGC that could be useful in establishing the diagnosis. This study evaluated the immunohistochemical profile of 2 cases of AGC in comparison to anal glands from 11 hemorrhoidectomy specimens. Sections from the specimens were routinely processed and immunostained using commercial antibodies to cytokeratin (CK) 7, CK20, CK5/ 6, p63, CDX2, smooth muscle actin, calponin, heavy chain smooth muscle myosin, p53, and p16. In case 1 of AGC, radiation and chemotherapy preceded an abdominoperineal resection. In biopsies from this case, the neoplastic anal glands had a tubular pattern, whereas most glands in the resection specimen exhibited mucinous features. The histologic pattern in case 2 was tubular. Normal anal glands showed immunoreactivity for myoepithelial and basal cell markers CK5/6 and p63 in basal and parabasal cell layers and for CK7 in superficial cell layers. In contrast, both cases of AGC were negative for CK5/6 and p63 and were diffusely positive for CK7. Normal glands and both cases of AGC were negative for the intestinal differentiation marker CDX2, CK20, smooth muscle actin, calponin, smooth muscle myosin heavy chain, p16, and p53. Our data suggest that loss of p63 and CK5/6 expression is a feature of AGC. Anal gland carcinoma shares negativity for CDX2 and CK7+/CK20− profile with normal anal glands. No evidence of myoepithelial cells was found in normal or malignant anal glands. These data may be useful in establishing the diagnosis of AGC.

Fístula anal de origen criptoglandular. Opciones terapéuticas

Anal fistula is a frequent condition. The most commonly accepted origin is infectious. The most widely used classification is based on cryptoglandular theory and on the position of the fistulous tract in relation to the anal sphincter. Physical examination will help to identify the type of fistula and allow its treatment to be planned. The most widely used complementary tests are endoanal ultrasound and magnetic resonance imaging. We review the various therapeutic options and their results, especially fistulotomy, endorectal advancement flap, use of sedal, anodermal advancement flap, sphincterorrhaphy with sphincter repair, and fibrin glue.

Potential clinical implications of direction of a trans-sphincteric anal fistula track

Background

The longitudinal direction of a trans-sphincteric anal fistula track through the anal sphincter complex may have implications regarding fistulotomy.

Methods

The angle of the track of trans-sphincteric fistulas relative to the longitudinal axis of the anal canal was measured before operation by means of magnetic resonance imaging (MRI) in 46 patients. This was compared with the findings at operation.

Results

The track passed cranially as well as laterally at an acute angle (less than 90°) in 23 patients while it passed either transversely or caudally at an obtuse angle (90° or more) in the remaining 23. The internal opening was significantly higher in relation to the dentate line (above in eight patients, at the dentate line in 14 and below in one patient) when the track was acute than when it was obtuse (above in one, at the dentate line in 17 and below in five patients) (P = 0·004). The fistula track crossed the sphincter at a median angle of 35°, 95° and 132° from internal openings sited above, at and below dentate line level respectively (P = 0·002).

Conclusion

Fistula tracks passed cranially and laterally through the sphincter complex in half of these patients, and were most acutely angled on MRI when internal openings were situated above the dentate line. Preoperative MRI might alert surgeons to the potential hazard of fistulotomy being more extensive than anticipated from simple palpation of the level of the internal opening.

Imaging anal fistula

The management of fistula-in-ano has been based on digital examination and operative findings. MR imaging has shown significant limitations to this approach, particularly in the management of recurrent fistula. The most cost-effective approach may be using a combination of endosonography and MR imaging. Preoperative confirmation of fistula complexity facilitates surgery planning of sphincter saving techniques and prevents sepsis being missed, which has been shown to reduce recurrence. Imaging has a significant role to play in this condition to improve patient outcome.

Anal neoplasms

A common theme in most anal neoplasms appears to be a delay in diagnosis due to confusion with more common, benign conditions. Thus, the clinician must maintain a high index of suspicion when evaluating lesions of the anal canal and margin. The use of primary chemoradiation for SCC of the anal canal has resulted in equivalent, if not superior, local control and survival compared with radical surgery, and results in sphincter preservation in over two thirds of cases. Nevertheless, abdominoperineal resection still plays an important role in salvage of treatment failures, and also for patients who are unlikely to tolerate chemoradiation or have pre-existing impaired continence. Recent studies indicate that variations in chemotherapeutic agents and radiation technique might potentially produce even better results. The prognosis for anorectal melanoma, as well as for small cell and undifferentiated tumors, continues to be poor. Fortunately, these are relatively rare tumors.

Anorectal anatomy and physiology

Knowledge of anorectal anatomy is essential for understanding the normal function of the anorectum. Its physiology is more complex, however. The maintenance of continence depends on several factors, and today clinicians have a better understanding of the usual sequence of events that leads to defecation. The extensive number of investigative techniques that have evolved have permitted better understanding of the disorders of the anal sphincters, rectum, and pelvic floor.